Eutopic Endometrium Immune Changes Involved in Development and Progression of Endometriosis: A Review

Numerous abnormalities of the endometriosis eutopic endometrium contribute to the initiation and development of ectopic lesions. It is also believed that among the complex causes of the disease, systemic immunological disorders play a significant role. Therefore, this literature review aims to summarize the current knowledge on immunological alterations in the endometriosis eutopic endometrium and the impact of these changes on the progression of this disease. The reviewed studies mostly indicated a pro-inflammatory immunological profile within this tissue. This was evidenced by a predominance of M1 macrophages, which have a pro-inflammatory character and elevated levels of pro-inflammatory cytokines such as interleukin-1 (IL-1) or IL-6. Additionally, an increased number of cytotoxic T lymphocytes and a positive correlation between B lymphocyte levels and the presence of endometriosis have been observed. Some changes in T cells and natural killer (NK) cells receptors, which possibly determine endometriosis development, have been described. Several studies have also revealed that patients with endometriosis exhibit reduced presence of dendritic cells in the eutopic endometrium of affected individuals, which may impair uterine cavity clearance during menstruation and contribute to ectopic lesion formation. In summary, current data indicate a pivotal role of the endometrial immune environment in disease progression, but further research is needed to drive development of immunological treatment in endometriosis management.